TEMPERATURE DEPENDENCY OF VISCOELASTIC PROPERTIES OF A LOW-FAT SOFT CHEESE AFTER FROZEN STORAGE

MEZA, BÁRBARA E.; DE PIANTE VICÍN, DANIEL; VERDINI, ROXANA A.; RUBIOLO, AMELIA C.

Foz do Iguacu

Congreso; 16th IUFoST - World Congress of Food Science and Technology; 2012

IUFoST

The objective of this work was to analyze temperature dependency of the viscoelastic properties of a low-fat soft cheese after frozen storage. Commercial cheese bars were frozen and stored at -25 ºC during 33 days. After that, cheeses were thawed and stored at 6 ºC during 48 days for further ripening (frozen cheeses). Cheeses stored at 6 ºC during 48 days were used as control samples (control cheeses). Frequency sweeps (0.01-10 Hz) in the linear viscoelastic region at several temperatures (10, 20, 30, 40, and 50 ºC) were carried out in triplicate. Elastic modulus (G'), viscous modulus (G"), complex modulus (|G*|), and complex viscosity (|η*|) were determined. Time-temperature superposition model (TTS) was applied in order to analyze G' and G" values. Weak gel model for foods (|G*|=AF*f^z) was used to study values of |G*|. Temperature dependency of |η*| at 1 Hz was analyzed with an Arrhenius type equation. Statistical analysis was done using ANOVA. TTS was satisfactorily applied to overlap G' and G" values at low temperatures (10 to 30 ºC). Activation energy of |η*| for frozen cheeses was lower than for control cheeses, suggesting lower resistant to break up of cheese microstructure. Weak gel model parameters, z (number of interactions) and AF (strength of interactions), decreased as temperature increased from 30 to 50 ºC in both frozen and control cheeses. Also, z values were lower in frozen cheeses than in control cheeses, suggesting that frozen cheeses presented lower number of interactions than control cheeses.